The subject invention is directed toward the valve art and, more particularly, to a flap-type valve element and method of forming same. The invention is especially suited for forming valve flaps for pressure relief valves of the type used to relieve air pressure in vehicle passenger compartments.
Flap-type valves are commonly used as pressure relief valves in motor vehicle passenger compartments to maintain the compartments at ambient air pressure and to relieve air pressure build-up which results during operation of intake vent fans, door closing, and the like. To assure proper flexing and adequate sealing, the flap valve elements have generally been formed from soft elastomeric or rubbery material such as polyvinyl chloride, polyethylene, or the like. Often, such flap elements exhibit a tendency to warp on initial use and to further warp or deform after long term normal use.